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Activity courtesy of TeachEngineering.org, contributed by the Integrated Teaching and Learning Program, College of Engineering, University of Colorado, Boulder.

Summary

In this activity, students in grades 9-11 learn how engineers harness the energy of the wind by following the engineering design process to create and test two prototype wind turbines. They also learn about where to place a wind turbine for maximum effectiveness, and weigh the advantages and disadvantages compared with other energy sources.

Grade level: 9 – 11

Time: 200 minutes (conduct this as an in-depth design activity over 3 to 4 class periods)

Cost: $3 per group

Engineering Connection

Engineers are responsible for developing, designing, testing, and improving ways in which electricity is generated for our homes and businesses. One way to generate power is to harness the energy of the wind using a wind turbine. Civil, mechanical, and electrical engineers work together to design and test wind turbines, including determining the most ideal locations for wind farms and the most efficient turbine designs for specific conditions.

Describe how wind turbines transfer the energy of the wind into electricity.

Compare and contrast two different types of wind turbines.

Evaluate the advantages and disadvantages for using wind power.

Use the engineering design process to create prototype wind turbines.

Standards

International Technology and Engineering Educators Association

K. A prototype is a working model used to test a design concept by making actual observations and necessary adjustments. (Grades 9 – 12)

M. Energy resources can be renewable or nonrenewable. (Grades 9 – 12)

Next Generation ScienceStandards [High School]

Energy (Physical Sciences): Design, build, and refine a device that works within given constraints to convert one form of energy into another form of energy.

Create a computational model to calculate the change in the energy of one component in a system when the change in energy of the other component(s) and energy flows in and out of the system are known.

Engineering Design: Design a solution to a complex, real-world problem by breaking it down into smaller, more manageable problems that can be solved through engineering.

Evaluate a solution to a complex, real-world problem based on prioritized criteria and trade-offs that account for a range of constraints, including costs, safety, reliability and aesthetics as well as possible social, cultural, and environmental impacts.

[Note: A 49-minute video from KidWind provides comprehensive overview of wind power, from historical irrigation systems to modern wind farms.]

Vertical-Axis Wind Turbines (VAWTs) are very rare today. The most prevalent is the Darrieus turbine, which looks somewhat like an egg beater. The chief characteristic of a VAWT is that the blades spin a shaft that is aligned vertically (perpendicular) to the ground. VAWTs have two main disadvantages:

They cannot start spinning on their own and require a boost from an electrical system, and

They are held up by wires, limiting their height and thus winds they can access.

VAWTs are, however, always aligned with the wind, so the blades still rotate even if the wind changes direction. Plus all of the turbine equipment (the generator, gearbox, etc.) is located on the ground, which makes maintenance easier, but also takes up more ground space, which can be a disadvantage in certain locations.

Horizontal-Axis Wind Turbines (HAWTs) are often used for large-scale electrical utility production using wind energy. The optimal wind speed for these turbines is about 15 m/s. At about 20 m/s, most turbines shut down because of the danger to the structure due to high wind speeds. HAWTs are more efficient than VAWTs, which means they generate more electricity if placed in the same spot, Another advantage is that they can reach much higher elevations where wind speeds are greater and generally have a smaller footprint on the ground.

Having all the turbine components located hundreds of feet above the ground makes maintenance more difficult, however. HAWTs also must be adjusted to the direction of the wind. T; this requires designing a system that tracks the wind and automatically moves the blades into optimum position to catch the most wind.

In this activity, each group creates a turbine on their own cylindrical block of wood and then takes turns placing their turbines on the class turbine testing device(s) to measure voltage.

With the Students

Divide the class into groups of two or three students each.

Distribute the worksheets and blocks of wood.

In a class discussion, generate the problem that the students are trying to solve by designing wind turbines; this should include how to generate electricity for a house using a renewable energy source.

In groups, have students brainstorm designs for a vertical-axis turbine and a horizontal-axis turbine Possible questions to ask: How many blades? How to space them? From what material should we make the blades? What shape for the blades? Have students record all their brainstorm ideas on their worksheets.

From a review of their brainstorming exercise results, have each group choose one vertical and one horizontal design to build for their wind turbine models. Direct them to draw their designs on their worksheets and explain why they chose those designs.

Next, have each group build their turbines. Use the shorter cylindrical wood blocks for the horizontal-axis wind turbine. Use the longer cylindrical wood blocks for the vertical-axis turbine. Attach the turbine blades onto the side of the wood opposite the side with the hole drilled into it.

7. Once a group has finished building their designs, have them test them. To do this, have them stick the end of the model turbine through the PVC pipe on the testing device and onto the shaft of the motor. You may want to tape the front end of the testing device to the surface it is sitting on in order to prevent movement during testing. Once the turbine is connected, have one student operate the fan at each speed setting.

8. Have each group take turns testing their turbine designs at three different fan speeds, recording the output data on their worksheets.

9. Repeat the testing procedure for the other turbines, again recording the data on their worksheets.

10. Have students complete the calculations and analysis on their worksheets. [Click HERE for answers to to Wind Turbine Worksheet.]

11. Conclude with a class discussion to review and compare the groups’ findings. What improvements would they make? Where would they locate turbines near their energy-efficient houses?

12. Have student teams present their designs to the rest of the class. They should include descriptions of how well the wind turbines worked, which type of turbine worked best, and what improvements they might make to their designs.

Troubleshooting tips.

Some motors have easy-to-spot connectors (two pieces of metal sticking out of the motor with a hole in the middle) that make attaching wires and multimeters/voltmeters to the motor leads straightforward, while others do not. If using a motor in which the connectors are absent on the motor, look for (at least) two slits for connectors on opposite sides of the motor. Have students place the leads of the wires or multimeters in two of these slits. If more than two slits, have students place the leads in one pair of the slits and turn the shaft of the motor manually. If the multimeter/voltmeter reads a voltage or current when the shaft spins, then these are the connectors. If it does not, then the other pair of slits is the connector. Have students check the motor for a voltage and current reading on the multimeter/voltmeter.

One easy way to measure voltage from the motor is to attach electrical wire to the motor connectors and use alligator clips on the ends of the multimeter/voltmeter leads. You can create one or more testing stations this way, and the students can just attach their wind turbines to the set-up.

Activity Extensions

Have students research the role of aerodynamics on wind turbines. Assign them to write a paragraph or two on the effects of forces such as lift and drag on modern turbines.

Activity Scaling

For younger students, eliminate the mathematical analysis from the worksheet.

For older or more advanced students, have them write paragraphs detailing the materials and features of their turbine designs and why they designed them the way they did.

Exploring Wind Power. This comprehensive list of resources from the National Energy Education Development Project includes a teacher’s guide with curriculum, standards-based activities, and other ideas for learning about wind power.

4H: Power of the Wind Online resource to supplement The Power of the Wind National 4-H curriculum designed to help middle school students learn about the wind and its uses; design, build, and test wind-powered devices; and explore wind as a potential energy source.

Wind 101. (VIDEO) Not very glitzy, but KidsWind video on alternative energy covers everything from how many light bulbs a megawatt or kilowatt of energy could power to where and how wind turbines are generating electricity. [Vimeo, 49:23]

Wind Power. eGFI adapted these inquiry-based activities from the PBS show NOW with Bill Moyers. They are designed to help high-school students discover the basics of wind power technology by building and refining a wind turbine.